1. Field of the Invention
The present invention relates to a supporting structure of a floating magnetic head device installed in, for example, a hard disk drive or an optical disk drive, and, more particularly, to a supporting structure of a magnetic head device in which torsional resonance does not occur easily, even when the spring constant of a load beam which rockably supports a head body is reduced.
2. Description of the Related Art
FIG. 4 is a plan view of a conventional magnetic head device for use in a hard disk drive.
The magnetic head device comprises a head body 1 and a supporting member 2 which supports the head body 1.
The head body 1 includes a slider 3 opposing a recording medium, such as a hard disk, with a thin film magnetic element (not shown) being provided at a trailing side end surface of the slider 3. The slider 3 is made of, for example, a ceramic material. The thin film magnetic element comprises a MR head (read head) and an inductive head (write head). The MR head detects any magnetic field leakage from a recording medium, such as a hard disk, by making use of the magneto-resistive effect in order to read a magnetic signal. The inductive head includes, for example, a coil formed into a pattern.
The supporting member 2 comprises a load beam 5 and a flexure 6.
The load beam is composed of a plate spring. As shown in FIG. 4, bent portions 5a are formed on both sides of one end of the load beam 5 so as to extend a certain distance from the one end. The portion of the load beam 5 extending from the starting side and terminating side of the bent portions 5a is the highly rigid portion 5b. A spherical pivot 17 is formed near one end of a flat portion 5c, formed between the bent portions 5a, so as to extend downward, in FIG. 4. In addition, a positioning hole 8 used for adjusting the position of a flexure (described later) is formed in the flat portion 5c.
The load beam 5 includes a resiliently deformable section 5d formed from the rear end portion of the flat portion 5c and integrally therewith. A mount member 10 is mounted onto the stem end of the load beam 5, and has fixing holes 11 used for fixing the load beam 5 to, for example, an actuating arm.
The flexure 6 is composed of a thin plate spring, and comprises a fixing portion 6a and a cantilever 6b. As shown in FIG. 4, a positioning hole 9 is formed in the fixing portion 6a. After aligning the positioning hole 9 and the positioning hole 8 in the load beam relative to each other, the fixing portion 6a is affixed to the bottom surface of the load beam 5 by, for example, spot welding. The cantilever 6b corresponds to the portion separated by a slot formed in one end of the flexure 6. The top surface of the cantilever 6b is abutted against the pivot 17 of the load beam 5. The resiliency of the cantilever 6b allows the head body 1, bonded to the bottom surface of the cantilever 6b, to freely change its posture on a bottommost point B, as a fulcrum, of the pivot 17.
When a recording medium, such as a hard disk or a magneto-optical disk, is stationary, the load beam 5 exerts a resilient pressing force on the head body 1 of the magnetic head device, causing it to be biased towards the recording medium. When the recording medium starts rotating, air current flows between the head body 1 and the recording medium, and produces a floating force, which is exerted to the bottom surface of the head body 1, causing it to float above the recording medium. In the floated state, the thin film magnetic element, provided at the slider 3 of the head body 1, either records a magnetic signal on the recording medium or reads the magnetic signal recorded on the recording medium.
In recent years, however, the sliders 3 are becoming smaller (or lighter). Therefore, in order to make the slider 3 float properly, while it is sliding along a recording medium, it is necessary to reduce the amount of pressing force that the load beam 5 exerts onto the slider 3.
In order to reduce the pressing force, the spring constant of the load beam 5 must be reduced. Conventionally, the spring constant was made smaller, for example, by making the load beam thinner, or by reducing the cross sectional area of the resiliently deformable section 5d of the load beam 5 in a widthwise direction thereof.
However, making the load beam 5 thinner causes the load a beam 5 as a whole to become less rigid, so that, for example, during a seeking operation,.the load beam 5 gets deflected in the seeking direction, resulting in, for example, less accurate detection of a track position. This causes tracking to be performed less accurately.
The structure shown in FIG. 5 is the most conventionally used structure for reducing the cross sectional area of the resiliently deformable section 5d of the load beam 5 in the widthwise direction thereof. This type of load beam is disclosed, for example, in Japanese Examined Patent Publication No. 8-23976.
FIG. 5 is an enlarged partial plan view of the structure of the portion around the resiliently deformable section 5d of the load beam 5.
As shown in FIG. 5, a large slot 18 is formed in the center of the resiliently deformable section 5d, whereby two legs 5f are formed on the resiliently deformable section 5d.
In such a structure, however, the legs 5f of the resiliently deformable section 5d easily resonate in a twisting direction, so that, for example, during a seeking operation, the load beam 5 gets deflected with respect to the twisting direction, making the floating posture of the head body 1 unstable. This, for example, causes tracking to be performed less accurately, just as in the case where the load beam 5 is made thinner.